Various vibration control measures have been taken for power transmission shafts for transmitting power from engines. For instance, the drive shaft may be equipped with a dynamic damper consisting of a spring and mass system attached to the drive shaft which is tuned to the frequency of the vibration of the drive shaft which is desired to be controlled. The dynamic damper changes the resonance property of the drive shaft so as to suppress the oscillation level at the original resonance frequency of the drive shaft. With the aim of suppressing the resonant vibration of the drive shaft, the drive shaft may be divided into two segments each of which are separately supported by the vehicle body. By thus reducing the span of the drive shaft, the resonance frequency of each span is raised, in some cases, well above the frequency of the vibration induced by the rotation of the drive shaft.
However, a dynamic damper requires a substantial mounting space, and adds to the mass of the drive shaft. Also, when the resonance frequency of the drive shaft is relatively low, the spring constant of the spring member of the dynamic damper is required to be so reduced that the durability of the dynamic damper could be impaired. When the drive shaft is divided into two segments, a bearing arrangement has to be provided for each segment, and this requires an increase in the number of required component parts such as a coupling and bearings. In either case, the rotating objects have to be balanced for rotation after these measures are taken, and this adds to the cost and labor required for assembling the motor vehicles.